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Electrolytic conduction
Electrolytic conduction refers to conduction with the help of two electrolytes. Electrolytes are nothing but a solution of a substance that has free ions in the valence band of the atom. These ions are unpaired and free to move. When unpaired ions move towards oppositely charged substances, there is a flow of current, which is termed, conduction.
The mechanism, in simple words, is when we give current to electrodes, the unpaired ions move to opposite electrodes. This gives rise to conductivity. There are also some effects of other situations such as pressure, temperature, electricity, etc. These situations enhance and de-enhance the process in their own way. We’re going to learn all the things further.
How exactly do electrolytes conduct electricity?
Consider a container, in which there are two electrodes(cathode and anode) immersed in an electrolytic solution of two substances. Suppose the two electrolyte solutions are A and B. And the two electrodes consist of the same substance, which is in an electrolytic solution. The two electrodes(cathode and anode) are connected through the wire in which there could be a passage of electric current.
Now when the electricity is passed through the conducting wire, the potential difference is created. When the potential difference is created, the positive free ions of substance A in the electrolyte go towards the negative ions of substance B. and get stuck to electrode B.
Similarly, the negative ions of substance B move towards electrode A and get stuck there. In this way, there is a movement of positive and negative ions, the conduction produced; this process is called Electrolytic conduction. This is a brief mechanism about how electrolytic conduction works.
Mathematically Electrolytic conduction expressed as given below
G = 1/R = 1/. A/l
Where G = electrolytic conduction
R = resistance
Ρ = specific resistance
A = cross section area of electrodes
l = distance between electrodes
What are electrolytes?
Electrolytes are substance which help to conduct electricity with help of ions. The conductivity of an electrolyte depends on the type of electrolyte. The electrolytic conduction happens due to the movement of free ions having different charges, which move towards oppositely charged electrodes that are cathode and anode. Cathode and anode are positively charged and negatively charged electrodes in a circuit. The electrolytes are further divided in their ability to conduct and movement.
If we move towards the nature of electrolytic substances, they are classified as strong and weak acidic electrolytes and strong and weak basic electrolytes. Examples of strong acidic electrolytes are HCl, HI, HBr, and strong basic electrolytes are NaOH, KOH, Ba(OH)2, etc. Examples of weak acidic electrolytes are HF, H2CO3 (carbonic acid), HC2H3O2 (acetic acid), H3PO4 (phosphoric acid), etc. and weak basic electrolytes are C5H5N (pyridine), NH3 (ammonia), etc.
Solutions that are used as electrolytes
The types of solutions which have free ions in them, irrespective of positive and negative charges, and have some net charge or ionic movement, are used as electrolytes in the process of electrolytic conduction.
Another way of choosing an electrolytic solution is to choose substances having some or more impurities. This will make the solution conductive in its own manner.
Some majorly used electrolytes are potassium, chloride, sodium, magnesium, phosphate, and calcium.
Factors on which conductivity of electrolytic solution depends
There are a few factors on which conductivity depends.
- Temperature
- Mobility of ions
- Viscosity of electrolyte
- Dimension of an electrolytic cell
- The concentration of ions in electrolytic cells
The factors are interrelated with each other. Let’s learn about them briefly.
Temperature
When we increase the temperature of the solution, it will adversely affect the decrease in the viscosity of the electrolytic solution and it will increase the mobility of the ions in the electrolytic solution. This makes the ions move faster and make the conduction faster.
In short, there will be an increase in the electrolytic conductivity of the solution. And make the process faster.
On the other hand, if we decrease the temperature. The mobility of ions decreases and makes the process slower. So, we can conclude that temperature and conductivity are directly proportional to each other.
Mobility of ions
Mobility of ions means at how much speed the ion can move. Mobility is defined as the drift velocity of electrons or ions. If we give heat, the mobility increases. That is, the drift velocity of ions increases, and this leads to the higher conductivity of the cell. If we decrease the temperature, the mobility decreases, which means the velocity of ions decreases, and conductivity also decreases.
Viscosity of electrolyte
A fluid’s viscosity is the measure of how resistant it is to deformation at a certain pace. Its colloquial equivalent in liquids is “thickness”: syrup, for example, has a higher viscosity than water.
The internal frictional force that emerges between adjacent layers of fluid in relative motion can be thought of as viscosity. When a viscous fluid is driven into a tube, for example, it flows faster near the axis than it is at the tube’s walls. Experiments reveal that within this instance, some stress (such as a pressure difference between the tube’s two ends) is required to keep the flow going. This is owing to the belief that a push is necessary to overcome the friction between the fluid layers, which are in relative motion. The compensating force is proportional to the fluid’s viscosity in a tube with a steady rate of flow.
When the viscosity is high, there is a low flow of ions, or we can say it hinders the flow of ions, this makes conduction slow. And when there is a low viscosity, there is not much hindrance so, ions can make their movements easily. Hence, the flow of ions is high.
So, we can say viscosity and conductivity are inversely proportional to each other.
Dimensions of an electrolytic cell
The dimension of an electrolytic cell refers to how big or small the whole construction is. The whole construction of an electrolytic cell consists of electrodes, conducting wire, container, and amount of electrolyte. These all things made electrolytic cells.
If the size of the container is big, the electrons or ions will need to cover more distance and will require more time to perform the process. This will delay the process of electrolytic cells.
So we conclude that if the dimensions are more, the process will require more time to complete. And this delays the rate of electrolytic cells.
The concentration of ions in an electrolytic cell
The concentration of ions also affects the time rate of the process of an electrolytic cell. Consider if the amount of solution of electrolyte is more in the respective electrolytic cell, then ions will require more time to get stuck to the opposite electrode in the cell.
Hence, if the amount of an electrolyte is more, then the rate of completion of the process will be more. And on the other hand, if the amount of an electrolyte in the cell is less, then the required time to complete the process will also be less.
The concentration of ions in an electrolytic cell is directly proportional to the rate of completion of the electrolytic process. And the conduction will be more rapid.
Molar conductivity
Molar conductivity is a critical theory to understand. The meaning of molar conductivity is simple; it’s an expression with which the conductivity is measured.
Molar conductivity definition; is a ratio of the conductivity to that of molar concentration. In other words, if we divide the conductivity of an electrolytic cell with the molar concentration of an electrolyte, then it is known as molar conductivity.
Mathematically Molar conductivity expressed as below
m = KC
m (S m2 mol-1) = K (Sm-1) / 1000Lm-3 x Molarity (mol.L-1)
- The units of is Sm2 molL-1.
Conclusion
Supplying an electrical potential across the electrodes triggers an internal chemical reaction between the electrodes and the electrolyte solution ions that activate an electrolytic cell. This is referred to as electrolysis. Electrolysis is a task that includes sending an electric current through an electrolyte to simulate chemical reactions. Metal cations and spectator anions compensate for the electrolyte solution. The oxidation and reduction reactions are nonspontaneous and occur in the same container. The electrodes should always be connected to an external power source to proceed.
